When I double click a .c file (which is a text file, associated with "notepad.exe"), I see opening notepad with an empty file.
If I select the file, and press "F4", which is associated with notepad again ("%windir%\notepad.exe" under Settings -> Programs), the file is opened correctly.

Tested with FC 742, with the same settings, is working correctly (of course, it is working correctly with Explorer as well).
Strange enough, not all files behaves this way... for instance .txt files are opened fine, while .c file (which has the same association) are not.